| 1 |
/* |
| 2 |
* Written by Doug Lea with assistance from members of JCP JSR-166 |
| 3 |
* Expert Group and released to the public domain, as explained at |
| 4 |
* http://creativecommons.org/publicdomain/zero/1.0/ |
| 5 |
*/ |
| 6 |
|
| 7 |
package java.util.concurrent; |
| 8 |
|
| 9 |
import java.util.Deque; |
| 10 |
import java.util.Iterator; |
| 11 |
import java.util.NoSuchElementException; |
| 12 |
|
| 13 |
/** |
| 14 |
* A {@link Deque} that additionally supports blocking operations that wait |
| 15 |
* for the deque to become non-empty when retrieving an element, and wait for |
| 16 |
* space to become available in the deque when storing an element. |
| 17 |
* |
| 18 |
* <p>{@code BlockingDeque} methods come in four forms, with different ways |
| 19 |
* of handling operations that cannot be satisfied immediately, but may be |
| 20 |
* satisfied at some point in the future: |
| 21 |
* one throws an exception, the second returns a special value (either |
| 22 |
* {@code null} or {@code false}, depending on the operation), the third |
| 23 |
* blocks the current thread indefinitely until the operation can succeed, |
| 24 |
* and the fourth blocks for only a given maximum time limit before giving |
| 25 |
* up. These methods are summarized in the following table: |
| 26 |
* |
| 27 |
* <table class="plain"> |
| 28 |
* <caption>Summary of BlockingDeque methods</caption> |
| 29 |
* <tr> |
| 30 |
* <th id="First" colspan="5"> First Element (Head)</th> |
| 31 |
* </tr> |
| 32 |
* <tr> |
| 33 |
* <td></td> |
| 34 |
* <th id="FThrow" style="font-weight:normal; font-style: italic">Throws exception</th> |
| 35 |
* <th id="FValue" style="font-weight:normal; font-style: italic">Special value</th> |
| 36 |
* <th id="FBlock" style="font-weight:normal; font-style: italic">Blocks</th> |
| 37 |
* <th id="FTimes" style="font-weight:normal; font-style: italic">Times out</th> |
| 38 |
* </tr> |
| 39 |
* <tr> |
| 40 |
* <th id="FInsert" style="text-align:left">Insert</th> |
| 41 |
* <td headers="First FInsert FThrow">{@link #addFirst(Object) addFirst(e)}</td> |
| 42 |
* <td headers="First FInsert FValue">{@link #offerFirst(Object) offerFirst(e)}</td> |
| 43 |
* <td headers="First FInsert FBlock">{@link #putFirst(Object) putFirst(e)}</td> |
| 44 |
* <td headers="First FInsert FTimes">{@link #offerFirst(Object, long, TimeUnit) offerFirst(e, time, unit)}</td> |
| 45 |
* </tr> |
| 46 |
* <tr> |
| 47 |
* <th id="FRemove" style="text-align:left">Remove</th> |
| 48 |
* <td headers="First FRemove FThrow">{@link #removeFirst() removeFirst()}</td> |
| 49 |
* <td headers="First FRemove FValue">{@link #pollFirst() pollFirst()}</td> |
| 50 |
* <td headers="First FRemove FBlock">{@link #takeFirst() takeFirst()}</td> |
| 51 |
* <td headers="First FRemove FTimes">{@link #pollFirst(long, TimeUnit) pollFirst(time, unit)}</td> |
| 52 |
* </tr> |
| 53 |
* <tr> |
| 54 |
* <th id="FExamine" style="text-align:left">Examine</th> |
| 55 |
* <td headers="First FExamine FThrow">{@link #getFirst() getFirst()}</td> |
| 56 |
* <td headers="First FExamine FValue">{@link #peekFirst() peekFirst()}</td> |
| 57 |
* <td headers="First FExamine FBlock" style="font-style:italic">not applicable</td> |
| 58 |
* <td headers="First FExamine FTimes" style="font-style:italic">not applicable</td> |
| 59 |
* </tr> |
| 60 |
* <tr> |
| 61 |
* <th id="Last" colspan="5"> Last Element (Tail)</th> |
| 62 |
* </tr> |
| 63 |
* <tr> |
| 64 |
* <td></td> |
| 65 |
* <th id="LThrow" style="font-weight:normal; font-style: italic">Throws exception</th> |
| 66 |
* <th id="LValue" style="font-weight:normal; font-style: italic">Special value</th> |
| 67 |
* <th id="LBlock" style="font-weight:normal; font-style: italic">Blocks</th> |
| 68 |
* <th id="LTimes" style="font-weight:normal; font-style: italic">Times out</th> |
| 69 |
* </tr> |
| 70 |
* <tr> |
| 71 |
* <th id="LInsert" style="text-align:left">Insert</th> |
| 72 |
* <td headers="Last LInsert LThrow">{@link #addLast(Object) addLast(e)}</td> |
| 73 |
* <td headers="Last LInsert LValue">{@link #offerLast(Object) offerLast(e)}</td> |
| 74 |
* <td headers="Last LInsert LBlock">{@link #putLast(Object) putLast(e)}</td> |
| 75 |
* <td headers="Last LInsert LTimes">{@link #offerLast(Object, long, TimeUnit) offerLast(e, time, unit)}</td> |
| 76 |
* </tr> |
| 77 |
* <tr> |
| 78 |
* <th id="LRemove" style="text-align:left">Remove</th> |
| 79 |
* <td headers="Last LRemove LThrow">{@link #removeLast() removeLast()}</td> |
| 80 |
* <td headers="Last LRemove LValue">{@link #pollLast() pollLast()}</td> |
| 81 |
* <td headers="Last LRemove LBlock">{@link #takeLast() takeLast()}</td> |
| 82 |
* <td headers="Last LRemove LTimes">{@link #pollLast(long, TimeUnit) pollLast(time, unit)}</td> |
| 83 |
* </tr> |
| 84 |
* <tr> |
| 85 |
* <th id="LExamine" style="text-align:left">Examine</th> |
| 86 |
* <td headers="Last LExamine LThrow">{@link #getLast() getLast()}</td> |
| 87 |
* <td headers="Last LExamine LValue">{@link #peekLast() peekLast()}</td> |
| 88 |
* <td headers="Last LExamine LBlock" style="font-style:italic">not applicable</td> |
| 89 |
* <td headers="Last LExamine LTimes" style="font-style:italic">not applicable</td> |
| 90 |
* </tr> |
| 91 |
* </table> |
| 92 |
* |
| 93 |
* <p>Like any {@link BlockingQueue}, a {@code BlockingDeque} is thread safe, |
| 94 |
* does not permit null elements, and may (or may not) be |
| 95 |
* capacity-constrained. |
| 96 |
* |
| 97 |
* <p>A {@code BlockingDeque} implementation may be used directly as a FIFO |
| 98 |
* {@code BlockingQueue}. The methods inherited from the |
| 99 |
* {@code BlockingQueue} interface are precisely equivalent to |
| 100 |
* {@code BlockingDeque} methods as indicated in the following table: |
| 101 |
* |
| 102 |
* <table class="plain"> |
| 103 |
* <caption>Comparison of BlockingQueue and BlockingDeque methods</caption> |
| 104 |
* <tr> |
| 105 |
* <td></td> |
| 106 |
* <th id="BQueue"> {@code BlockingQueue} Method</th> |
| 107 |
* <th id="BDeque"> Equivalent {@code BlockingDeque} Method</th> |
| 108 |
* </tr> |
| 109 |
* <tr> |
| 110 |
* <th id="Insert" rowspan="4" style="text-align:left; vertical-align:top">Insert</th> |
| 111 |
* <th id="add" style="font-weight:normal; text-align:left">{@link #add(Object) add(e)}</th> |
| 112 |
* <td headers="Insert BDeque add">{@link #addLast(Object) addLast(e)}</td> |
| 113 |
* </tr> |
| 114 |
* <tr> |
| 115 |
* <th id="offer1" style="font-weight:normal; text-align:left">{@link #offer(Object) offer(e)}</th> |
| 116 |
* <td headers="Insert BDeque offer1">{@link #offerLast(Object) offerLast(e)}</td> |
| 117 |
* </tr> |
| 118 |
* <tr> |
| 119 |
* <th id="put" style="font-weight:normal; text-align:left">{@link #put(Object) put(e)}</th> |
| 120 |
* <td headers="Insert BDeque put">{@link #putLast(Object) putLast(e)}</td> |
| 121 |
* </tr> |
| 122 |
* <tr> |
| 123 |
* <th id="offer2" style="font-weight:normal; text-align:left">{@link #offer(Object, long, TimeUnit) offer(e, time, unit)}</th> |
| 124 |
* <td headers="Insert BDeque offer2">{@link #offerLast(Object, long, TimeUnit) offerLast(e, time, unit)}</td> |
| 125 |
* </tr> |
| 126 |
* <tr> |
| 127 |
* <th id="Remove" rowspan="4" style="text-align:left; vertical-align:top">Remove</th> |
| 128 |
* <th id="remove" style="font-weight:normal; text-align:left">{@link #remove() remove()}</th> |
| 129 |
* <td headers="Remove BDeque remove">{@link #removeFirst() removeFirst()}</td> |
| 130 |
* </tr> |
| 131 |
* <tr> |
| 132 |
* <th id="poll1" style="font-weight:normal; text-align:left">{@link #poll() poll()}</th> |
| 133 |
* <td headers="Remove BDeque poll1">{@link #pollFirst() pollFirst()}</td> |
| 134 |
* </tr> |
| 135 |
* <tr> |
| 136 |
* <th id="take" style="font-weight:normal; text-align:left">{@link #take() take()}</th> |
| 137 |
* <td headers="Remove BDeque take">{@link #takeFirst() takeFirst()}</td> |
| 138 |
* </tr> |
| 139 |
* <tr> |
| 140 |
* <th id="poll2" style="font-weight:normal; text-align:left">{@link #poll(long, TimeUnit) poll(time, unit)}</th> |
| 141 |
* <td headers="Remove BDeque poll2">{@link #pollFirst(long, TimeUnit) pollFirst(time, unit)}</td> |
| 142 |
* </tr> |
| 143 |
* <tr> |
| 144 |
* <th id="Examine" rowspan="2" style="text-align:left; vertical-align:top">Examine</th> |
| 145 |
* <th id="element" style="font-weight:normal; text-align:left">{@link #element() element()}</th> |
| 146 |
* <td headers="Examine BDeque element">{@link #getFirst() getFirst()}</td> |
| 147 |
* </tr> |
| 148 |
* <tr> |
| 149 |
* <th id="peek" style="font-weight:normal; text-align:left">{@link #peek() peek()}</th> |
| 150 |
* <td headers="Examine BDeque peek">{@link #peekFirst() peekFirst()}</td> |
| 151 |
* </tr> |
| 152 |
* </table> |
| 153 |
* |
| 154 |
* <p>Memory consistency effects: As with other concurrent |
| 155 |
* collections, actions in a thread prior to placing an object into a |
| 156 |
* {@code BlockingDeque} |
| 157 |
* <a href="package-summary.html#MemoryVisibility"><i>happen-before</i></a> |
| 158 |
* actions subsequent to the access or removal of that element from |
| 159 |
* the {@code BlockingDeque} in another thread. |
| 160 |
* |
| 161 |
* <p>This interface is a member of the |
| 162 |
* <a href="{@docRoot}/java.base/java/util/package-summary.html#CollectionsFramework"> |
| 163 |
* Java Collections Framework</a>. |
| 164 |
* |
| 165 |
* @since 1.6 |
| 166 |
* @author Doug Lea |
| 167 |
* @param <E> the type of elements held in this deque |
| 168 |
*/ |
| 169 |
public interface BlockingDeque<E> extends BlockingQueue<E>, Deque<E> { |
| 170 |
/* |
| 171 |
* We have "diamond" multiple interface inheritance here, and that |
| 172 |
* introduces ambiguities. Methods might end up with different |
| 173 |
* specs depending on the branch chosen by javadoc. Thus a lot of |
| 174 |
* methods specs here are copied from superinterfaces. |
| 175 |
*/ |
| 176 |
|
| 177 |
/** |
| 178 |
* Inserts the specified element at the front of this deque if it is |
| 179 |
* possible to do so immediately without violating capacity restrictions, |
| 180 |
* throwing an {@code IllegalStateException} if no space is currently |
| 181 |
* available. When using a capacity-restricted deque, it is generally |
| 182 |
* preferable to use {@link #offerFirst(Object) offerFirst}. |
| 183 |
* |
| 184 |
* @param e the element to add |
| 185 |
* @throws IllegalStateException {@inheritDoc} |
| 186 |
* @throws ClassCastException {@inheritDoc} |
| 187 |
* @throws NullPointerException if the specified element is null |
| 188 |
* @throws IllegalArgumentException {@inheritDoc} |
| 189 |
*/ |
| 190 |
void addFirst(E e); |
| 191 |
|
| 192 |
/** |
| 193 |
* Inserts the specified element at the end of this deque if it is |
| 194 |
* possible to do so immediately without violating capacity restrictions, |
| 195 |
* throwing an {@code IllegalStateException} if no space is currently |
| 196 |
* available. When using a capacity-restricted deque, it is generally |
| 197 |
* preferable to use {@link #offerLast(Object) offerLast}. |
| 198 |
* |
| 199 |
* @param e the element to add |
| 200 |
* @throws IllegalStateException {@inheritDoc} |
| 201 |
* @throws ClassCastException {@inheritDoc} |
| 202 |
* @throws NullPointerException if the specified element is null |
| 203 |
* @throws IllegalArgumentException {@inheritDoc} |
| 204 |
*/ |
| 205 |
void addLast(E e); |
| 206 |
|
| 207 |
/** |
| 208 |
* Inserts the specified element at the front of this deque if it is |
| 209 |
* possible to do so immediately without violating capacity restrictions, |
| 210 |
* returning {@code true} upon success and {@code false} if no space is |
| 211 |
* currently available. |
| 212 |
* When using a capacity-restricted deque, this method is generally |
| 213 |
* preferable to the {@link #addFirst(Object) addFirst} method, which can |
| 214 |
* fail to insert an element only by throwing an exception. |
| 215 |
* |
| 216 |
* @param e the element to add |
| 217 |
* @throws ClassCastException {@inheritDoc} |
| 218 |
* @throws NullPointerException if the specified element is null |
| 219 |
* @throws IllegalArgumentException {@inheritDoc} |
| 220 |
*/ |
| 221 |
boolean offerFirst(E e); |
| 222 |
|
| 223 |
/** |
| 224 |
* Inserts the specified element at the end of this deque if it is |
| 225 |
* possible to do so immediately without violating capacity restrictions, |
| 226 |
* returning {@code true} upon success and {@code false} if no space is |
| 227 |
* currently available. |
| 228 |
* When using a capacity-restricted deque, this method is generally |
| 229 |
* preferable to the {@link #addLast(Object) addLast} method, which can |
| 230 |
* fail to insert an element only by throwing an exception. |
| 231 |
* |
| 232 |
* @param e the element to add |
| 233 |
* @throws ClassCastException {@inheritDoc} |
| 234 |
* @throws NullPointerException if the specified element is null |
| 235 |
* @throws IllegalArgumentException {@inheritDoc} |
| 236 |
*/ |
| 237 |
boolean offerLast(E e); |
| 238 |
|
| 239 |
/** |
| 240 |
* Inserts the specified element at the front of this deque, |
| 241 |
* waiting if necessary for space to become available. |
| 242 |
* |
| 243 |
* @param e the element to add |
| 244 |
* @throws InterruptedException if interrupted while waiting |
| 245 |
* @throws ClassCastException if the class of the specified element |
| 246 |
* prevents it from being added to this deque |
| 247 |
* @throws NullPointerException if the specified element is null |
| 248 |
* @throws IllegalArgumentException if some property of the specified |
| 249 |
* element prevents it from being added to this deque |
| 250 |
*/ |
| 251 |
void putFirst(E e) throws InterruptedException; |
| 252 |
|
| 253 |
/** |
| 254 |
* Inserts the specified element at the end of this deque, |
| 255 |
* waiting if necessary for space to become available. |
| 256 |
* |
| 257 |
* @param e the element to add |
| 258 |
* @throws InterruptedException if interrupted while waiting |
| 259 |
* @throws ClassCastException if the class of the specified element |
| 260 |
* prevents it from being added to this deque |
| 261 |
* @throws NullPointerException if the specified element is null |
| 262 |
* @throws IllegalArgumentException if some property of the specified |
| 263 |
* element prevents it from being added to this deque |
| 264 |
*/ |
| 265 |
void putLast(E e) throws InterruptedException; |
| 266 |
|
| 267 |
/** |
| 268 |
* Inserts the specified element at the front of this deque, |
| 269 |
* waiting up to the specified wait time if necessary for space to |
| 270 |
* become available. |
| 271 |
* |
| 272 |
* @param e the element to add |
| 273 |
* @param timeout how long to wait before giving up, in units of |
| 274 |
* {@code unit} |
| 275 |
* @param unit a {@code TimeUnit} determining how to interpret the |
| 276 |
* {@code timeout} parameter |
| 277 |
* @return {@code true} if successful, or {@code false} if |
| 278 |
* the specified waiting time elapses before space is available |
| 279 |
* @throws InterruptedException if interrupted while waiting |
| 280 |
* @throws ClassCastException if the class of the specified element |
| 281 |
* prevents it from being added to this deque |
| 282 |
* @throws NullPointerException if the specified element is null |
| 283 |
* @throws IllegalArgumentException if some property of the specified |
| 284 |
* element prevents it from being added to this deque |
| 285 |
*/ |
| 286 |
boolean offerFirst(E e, long timeout, TimeUnit unit) |
| 287 |
throws InterruptedException; |
| 288 |
|
| 289 |
/** |
| 290 |
* Inserts the specified element at the end of this deque, |
| 291 |
* waiting up to the specified wait time if necessary for space to |
| 292 |
* become available. |
| 293 |
* |
| 294 |
* @param e the element to add |
| 295 |
* @param timeout how long to wait before giving up, in units of |
| 296 |
* {@code unit} |
| 297 |
* @param unit a {@code TimeUnit} determining how to interpret the |
| 298 |
* {@code timeout} parameter |
| 299 |
* @return {@code true} if successful, or {@code false} if |
| 300 |
* the specified waiting time elapses before space is available |
| 301 |
* @throws InterruptedException if interrupted while waiting |
| 302 |
* @throws ClassCastException if the class of the specified element |
| 303 |
* prevents it from being added to this deque |
| 304 |
* @throws NullPointerException if the specified element is null |
| 305 |
* @throws IllegalArgumentException if some property of the specified |
| 306 |
* element prevents it from being added to this deque |
| 307 |
*/ |
| 308 |
boolean offerLast(E e, long timeout, TimeUnit unit) |
| 309 |
throws InterruptedException; |
| 310 |
|
| 311 |
/** |
| 312 |
* Retrieves and removes the first element of this deque, waiting |
| 313 |
* if necessary until an element becomes available. |
| 314 |
* |
| 315 |
* @return the head of this deque |
| 316 |
* @throws InterruptedException if interrupted while waiting |
| 317 |
*/ |
| 318 |
E takeFirst() throws InterruptedException; |
| 319 |
|
| 320 |
/** |
| 321 |
* Retrieves and removes the last element of this deque, waiting |
| 322 |
* if necessary until an element becomes available. |
| 323 |
* |
| 324 |
* @return the tail of this deque |
| 325 |
* @throws InterruptedException if interrupted while waiting |
| 326 |
*/ |
| 327 |
E takeLast() throws InterruptedException; |
| 328 |
|
| 329 |
/** |
| 330 |
* Retrieves and removes the first element of this deque, waiting |
| 331 |
* up to the specified wait time if necessary for an element to |
| 332 |
* become available. |
| 333 |
* |
| 334 |
* @param timeout how long to wait before giving up, in units of |
| 335 |
* {@code unit} |
| 336 |
* @param unit a {@code TimeUnit} determining how to interpret the |
| 337 |
* {@code timeout} parameter |
| 338 |
* @return the head of this deque, or {@code null} if the specified |
| 339 |
* waiting time elapses before an element is available |
| 340 |
* @throws InterruptedException if interrupted while waiting |
| 341 |
*/ |
| 342 |
E pollFirst(long timeout, TimeUnit unit) |
| 343 |
throws InterruptedException; |
| 344 |
|
| 345 |
/** |
| 346 |
* Retrieves and removes the last element of this deque, waiting |
| 347 |
* up to the specified wait time if necessary for an element to |
| 348 |
* become available. |
| 349 |
* |
| 350 |
* @param timeout how long to wait before giving up, in units of |
| 351 |
* {@code unit} |
| 352 |
* @param unit a {@code TimeUnit} determining how to interpret the |
| 353 |
* {@code timeout} parameter |
| 354 |
* @return the tail of this deque, or {@code null} if the specified |
| 355 |
* waiting time elapses before an element is available |
| 356 |
* @throws InterruptedException if interrupted while waiting |
| 357 |
*/ |
| 358 |
E pollLast(long timeout, TimeUnit unit) |
| 359 |
throws InterruptedException; |
| 360 |
|
| 361 |
/** |
| 362 |
* Removes the first occurrence of the specified element from this deque. |
| 363 |
* If the deque does not contain the element, it is unchanged. |
| 364 |
* More formally, removes the first element {@code e} such that |
| 365 |
* {@code o.equals(e)} (if such an element exists). |
| 366 |
* Returns {@code true} if this deque contained the specified element |
| 367 |
* (or equivalently, if this deque changed as a result of the call). |
| 368 |
* |
| 369 |
* @param o element to be removed from this deque, if present |
| 370 |
* @return {@code true} if an element was removed as a result of this call |
| 371 |
* @throws ClassCastException if the class of the specified element |
| 372 |
* is incompatible with this deque |
| 373 |
* (<a href="{@docRoot}/java.base/java/util/Collection.html#optional-restrictions">optional</a>) |
| 374 |
* @throws NullPointerException if the specified element is null |
| 375 |
* (<a href="{@docRoot}/java.base/java/util/Collection.html#optional-restrictions">optional</a>) |
| 376 |
*/ |
| 377 |
boolean removeFirstOccurrence(Object o); |
| 378 |
|
| 379 |
/** |
| 380 |
* Removes the last occurrence of the specified element from this deque. |
| 381 |
* If the deque does not contain the element, it is unchanged. |
| 382 |
* More formally, removes the last element {@code e} such that |
| 383 |
* {@code o.equals(e)} (if such an element exists). |
| 384 |
* Returns {@code true} if this deque contained the specified element |
| 385 |
* (or equivalently, if this deque changed as a result of the call). |
| 386 |
* |
| 387 |
* @param o element to be removed from this deque, if present |
| 388 |
* @return {@code true} if an element was removed as a result of this call |
| 389 |
* @throws ClassCastException if the class of the specified element |
| 390 |
* is incompatible with this deque |
| 391 |
* (<a href="{@docRoot}/java.base/java/util/Collection.html#optional-restrictions">optional</a>) |
| 392 |
* @throws NullPointerException if the specified element is null |
| 393 |
* (<a href="{@docRoot}/java.base/java/util/Collection.html#optional-restrictions">optional</a>) |
| 394 |
*/ |
| 395 |
boolean removeLastOccurrence(Object o); |
| 396 |
|
| 397 |
// *** BlockingQueue methods *** |
| 398 |
|
| 399 |
/** |
| 400 |
* Inserts the specified element into the queue represented by this deque |
| 401 |
* (in other words, at the tail of this deque) if it is possible to do so |
| 402 |
* immediately without violating capacity restrictions, returning |
| 403 |
* {@code true} upon success and throwing an |
| 404 |
* {@code IllegalStateException} if no space is currently available. |
| 405 |
* When using a capacity-restricted deque, it is generally preferable to |
| 406 |
* use {@link #offer(Object) offer}. |
| 407 |
* |
| 408 |
* <p>This method is equivalent to {@link #addLast(Object) addLast}. |
| 409 |
* |
| 410 |
* @param e the element to add |
| 411 |
* @throws IllegalStateException {@inheritDoc} |
| 412 |
* @throws ClassCastException if the class of the specified element |
| 413 |
* prevents it from being added to this deque |
| 414 |
* @throws NullPointerException if the specified element is null |
| 415 |
* @throws IllegalArgumentException if some property of the specified |
| 416 |
* element prevents it from being added to this deque |
| 417 |
*/ |
| 418 |
boolean add(E e); |
| 419 |
|
| 420 |
/** |
| 421 |
* Inserts the specified element into the queue represented by this deque |
| 422 |
* (in other words, at the tail of this deque) if it is possible to do so |
| 423 |
* immediately without violating capacity restrictions, returning |
| 424 |
* {@code true} upon success and {@code false} if no space is currently |
| 425 |
* available. When using a capacity-restricted deque, this method is |
| 426 |
* generally preferable to the {@link #add} method, which can fail to |
| 427 |
* insert an element only by throwing an exception. |
| 428 |
* |
| 429 |
* <p>This method is equivalent to {@link #offerLast(Object) offerLast}. |
| 430 |
* |
| 431 |
* @param e the element to add |
| 432 |
* @throws ClassCastException if the class of the specified element |
| 433 |
* prevents it from being added to this deque |
| 434 |
* @throws NullPointerException if the specified element is null |
| 435 |
* @throws IllegalArgumentException if some property of the specified |
| 436 |
* element prevents it from being added to this deque |
| 437 |
*/ |
| 438 |
boolean offer(E e); |
| 439 |
|
| 440 |
/** |
| 441 |
* Inserts the specified element into the queue represented by this deque |
| 442 |
* (in other words, at the tail of this deque), waiting if necessary for |
| 443 |
* space to become available. |
| 444 |
* |
| 445 |
* <p>This method is equivalent to {@link #putLast(Object) putLast}. |
| 446 |
* |
| 447 |
* @param e the element to add |
| 448 |
* @throws InterruptedException {@inheritDoc} |
| 449 |
* @throws ClassCastException if the class of the specified element |
| 450 |
* prevents it from being added to this deque |
| 451 |
* @throws NullPointerException if the specified element is null |
| 452 |
* @throws IllegalArgumentException if some property of the specified |
| 453 |
* element prevents it from being added to this deque |
| 454 |
*/ |
| 455 |
void put(E e) throws InterruptedException; |
| 456 |
|
| 457 |
/** |
| 458 |
* Inserts the specified element into the queue represented by this deque |
| 459 |
* (in other words, at the tail of this deque), waiting up to the |
| 460 |
* specified wait time if necessary for space to become available. |
| 461 |
* |
| 462 |
* <p>This method is equivalent to |
| 463 |
* {@link #offerLast(Object,long,TimeUnit) offerLast}. |
| 464 |
* |
| 465 |
* @param e the element to add |
| 466 |
* @return {@code true} if the element was added to this deque, else |
| 467 |
* {@code false} |
| 468 |
* @throws InterruptedException {@inheritDoc} |
| 469 |
* @throws ClassCastException if the class of the specified element |
| 470 |
* prevents it from being added to this deque |
| 471 |
* @throws NullPointerException if the specified element is null |
| 472 |
* @throws IllegalArgumentException if some property of the specified |
| 473 |
* element prevents it from being added to this deque |
| 474 |
*/ |
| 475 |
boolean offer(E e, long timeout, TimeUnit unit) |
| 476 |
throws InterruptedException; |
| 477 |
|
| 478 |
/** |
| 479 |
* Retrieves and removes the head of the queue represented by this deque |
| 480 |
* (in other words, the first element of this deque). |
| 481 |
* This method differs from {@link #poll() poll()} only in that it |
| 482 |
* throws an exception if this deque is empty. |
| 483 |
* |
| 484 |
* <p>This method is equivalent to {@link #removeFirst() removeFirst}. |
| 485 |
* |
| 486 |
* @return the head of the queue represented by this deque |
| 487 |
* @throws NoSuchElementException if this deque is empty |
| 488 |
*/ |
| 489 |
E remove(); |
| 490 |
|
| 491 |
/** |
| 492 |
* Retrieves and removes the head of the queue represented by this deque |
| 493 |
* (in other words, the first element of this deque), or returns |
| 494 |
* {@code null} if this deque is empty. |
| 495 |
* |
| 496 |
* <p>This method is equivalent to {@link #pollFirst()}. |
| 497 |
* |
| 498 |
* @return the head of this deque, or {@code null} if this deque is empty |
| 499 |
*/ |
| 500 |
E poll(); |
| 501 |
|
| 502 |
/** |
| 503 |
* Retrieves and removes the head of the queue represented by this deque |
| 504 |
* (in other words, the first element of this deque), waiting if |
| 505 |
* necessary until an element becomes available. |
| 506 |
* |
| 507 |
* <p>This method is equivalent to {@link #takeFirst() takeFirst}. |
| 508 |
* |
| 509 |
* @return the head of this deque |
| 510 |
* @throws InterruptedException if interrupted while waiting |
| 511 |
*/ |
| 512 |
E take() throws InterruptedException; |
| 513 |
|
| 514 |
/** |
| 515 |
* Retrieves and removes the head of the queue represented by this deque |
| 516 |
* (in other words, the first element of this deque), waiting up to the |
| 517 |
* specified wait time if necessary for an element to become available. |
| 518 |
* |
| 519 |
* <p>This method is equivalent to |
| 520 |
* {@link #pollFirst(long,TimeUnit) pollFirst}. |
| 521 |
* |
| 522 |
* @return the head of this deque, or {@code null} if the |
| 523 |
* specified waiting time elapses before an element is available |
| 524 |
* @throws InterruptedException if interrupted while waiting |
| 525 |
*/ |
| 526 |
E poll(long timeout, TimeUnit unit) |
| 527 |
throws InterruptedException; |
| 528 |
|
| 529 |
/** |
| 530 |
* Retrieves, but does not remove, the head of the queue represented by |
| 531 |
* this deque (in other words, the first element of this deque). |
| 532 |
* This method differs from {@link #peek() peek} only in that it throws an |
| 533 |
* exception if this deque is empty. |
| 534 |
* |
| 535 |
* <p>This method is equivalent to {@link #getFirst() getFirst}. |
| 536 |
* |
| 537 |
* @return the head of this deque |
| 538 |
* @throws NoSuchElementException if this deque is empty |
| 539 |
*/ |
| 540 |
E element(); |
| 541 |
|
| 542 |
/** |
| 543 |
* Retrieves, but does not remove, the head of the queue represented by |
| 544 |
* this deque (in other words, the first element of this deque), or |
| 545 |
* returns {@code null} if this deque is empty. |
| 546 |
* |
| 547 |
* <p>This method is equivalent to {@link #peekFirst() peekFirst}. |
| 548 |
* |
| 549 |
* @return the head of this deque, or {@code null} if this deque is empty |
| 550 |
*/ |
| 551 |
E peek(); |
| 552 |
|
| 553 |
/** |
| 554 |
* Removes the first occurrence of the specified element from this deque. |
| 555 |
* If the deque does not contain the element, it is unchanged. |
| 556 |
* More formally, removes the first element {@code e} such that |
| 557 |
* {@code o.equals(e)} (if such an element exists). |
| 558 |
* Returns {@code true} if this deque contained the specified element |
| 559 |
* (or equivalently, if this deque changed as a result of the call). |
| 560 |
* |
| 561 |
* <p>This method is equivalent to |
| 562 |
* {@link #removeFirstOccurrence(Object) removeFirstOccurrence}. |
| 563 |
* |
| 564 |
* @param o element to be removed from this deque, if present |
| 565 |
* @return {@code true} if this deque changed as a result of the call |
| 566 |
* @throws ClassCastException if the class of the specified element |
| 567 |
* is incompatible with this deque |
| 568 |
* (<a href="{@docRoot}/java.base/java/util/Collection.html#optional-restrictions">optional</a>) |
| 569 |
* @throws NullPointerException if the specified element is null |
| 570 |
* (<a href="{@docRoot}/java.base/java/util/Collection.html#optional-restrictions">optional</a>) |
| 571 |
*/ |
| 572 |
boolean remove(Object o); |
| 573 |
|
| 574 |
/** |
| 575 |
* Returns {@code true} if this deque contains the specified element. |
| 576 |
* More formally, returns {@code true} if and only if this deque contains |
| 577 |
* at least one element {@code e} such that {@code o.equals(e)}. |
| 578 |
* |
| 579 |
* @param o object to be checked for containment in this deque |
| 580 |
* @return {@code true} if this deque contains the specified element |
| 581 |
* @throws ClassCastException if the class of the specified element |
| 582 |
* is incompatible with this deque |
| 583 |
* (<a href="{@docRoot}/java.base/java/util/Collection.html#optional-restrictions">optional</a>) |
| 584 |
* @throws NullPointerException if the specified element is null |
| 585 |
* (<a href="{@docRoot}/java.base/java/util/Collection.html#optional-restrictions">optional</a>) |
| 586 |
*/ |
| 587 |
boolean contains(Object o); |
| 588 |
|
| 589 |
/** |
| 590 |
* Returns the number of elements in this deque. |
| 591 |
* |
| 592 |
* @return the number of elements in this deque |
| 593 |
*/ |
| 594 |
int size(); |
| 595 |
|
| 596 |
/** |
| 597 |
* Returns an iterator over the elements in this deque in proper sequence. |
| 598 |
* The elements will be returned in order from first (head) to last (tail). |
| 599 |
* |
| 600 |
* @return an iterator over the elements in this deque in proper sequence |
| 601 |
*/ |
| 602 |
Iterator<E> iterator(); |
| 603 |
|
| 604 |
// *** Stack methods *** |
| 605 |
|
| 606 |
/** |
| 607 |
* Pushes an element onto the stack represented by this deque (in other |
| 608 |
* words, at the head of this deque) if it is possible to do so |
| 609 |
* immediately without violating capacity restrictions, throwing an |
| 610 |
* {@code IllegalStateException} if no space is currently available. |
| 611 |
* |
| 612 |
* <p>This method is equivalent to {@link #addFirst(Object) addFirst}. |
| 613 |
* |
| 614 |
* @throws IllegalStateException {@inheritDoc} |
| 615 |
* @throws ClassCastException {@inheritDoc} |
| 616 |
* @throws NullPointerException if the specified element is null |
| 617 |
* @throws IllegalArgumentException {@inheritDoc} |
| 618 |
*/ |
| 619 |
void push(E e); |
| 620 |
} |
